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  #91  
Old June 10th, 2019, 20:14
lawsoncl lawsoncl is offline
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Re: Please try this with your XJ and tell me results?

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Originally Posted by soyjer View Post
I've been studying transmissions and torque converters, but I still haven't answered this question:
When an automatic transmission (especially the AW4) is in Neutral, does the input shaft spin as the impeller continues to drive the turbine, or is there some mechanism that holds the input shaft stationary?

The pump is always driven by the torque converter. The t/c has two sets of splines. One set is connected to the outside of the t/c body and always runs at engine rpm and drives the hydraulic pump. The second inner set is connected to the inside of the t/c and is the part that "slips". When the t/c lockup solenoid engages, these two lock together by means of a clutch in the t/c which prevents the normal slipping of the t/c.


I PM'd you some info on what the shafting and gearing looks like and which clutches are engaged when. In neutral all but one clutch is engaged and that's the clutch that disengages to give you OD.
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  #92  
Old June 10th, 2019, 21:02
soyjer soyjer is offline
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Re: Please try this with your XJ and tell me results?

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Originally Posted by lawsoncl View Post
The pump is always driven by the torque converter. The t/c has two sets of splines. One set is connected to the outside of the t/c body and always runs at engine rpm and drives the hydraulic pump. The second inner set is connected to the inside of the t/c and is the part that "slips". When the t/c lockup solenoid engages, these two lock together by means of a clutch in the t/c which prevents the normal slipping of the t/c.
I PM'd you some info on what the shafting and gearing looks like and which clutches are engaged when. In neutral all but one clutch is engaged and that's the clutch that disengages to give you OD.
Thanks...I do have the manual, but no info there about any mechanism dedicated to stopping input shaft rotation in Neutral (and Park?).
A shop owner/mechanic told me that there is such a mechanism in an AW4, but he referred me to a transmission shop that said no. Seems to be my typical experience, these days. If I can't find the answer online, I'll visit our local community college auto shop...maybe they will know.
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  #93  
Old June 10th, 2019, 21:52
lawsoncl lawsoncl is offline
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Re: Please try this with your XJ and tell me results?

Looking at the diagrams, the carrier just spins but isn't driving anything because none of the clutches are engaged. I don't see anything that would deliberately brake the input shaft, or that it would matter. How is the adjustment on the throttle body cable? If that's real tight you can get some harsh engagement.
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  #94  
Old June 10th, 2019, 22:26
soyjer soyjer is offline
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Re: Please try this with your XJ and tell me results?

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Originally Posted by lawsoncl View Post
Looking at the diagrams, the carrier just spins but isn't driving anything because none of the clutches are engaged. I don't see anything that would deliberately brake the input shaft, or that it would matter. How is the adjustment on the throttle body cable? If that's real tight you can get some harsh engagement.
Throttle cable has lots of puzzled mechanic's fingerprints on it...that's where their adventure begins, and then line pressure, motor mounts, differential, etc....then they say "transmission" and send me to transmission shops that are just as puzzled after repeating same checks and tests, basically.

My feeling that an un-braked input shaft in Neutral could cause the problem is based upon the momentum of the spinning input shaft in Neutral vs. no momentum of stationary input shaft in Reverse or Drive. Not saying it's necessarily the problem or that such a braking mechanism even exists...only saying that it fits the symptoms because pausing in Neutral is what causes the clunk/lurch to occur.
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  #95  
Old June 11th, 2019, 05:55
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devildog0 devildog0 is offline
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Please try this with your XJ and tell me results?

https://youtu.be/C1SBVUoLZfo

Have you adjusted the TV cable? No need to take it to a shop for this.



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  #96  
Old June 11th, 2019, 15:20
soyjer soyjer is offline
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Re: Please try this with your XJ and tell me results?

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Originally Posted by devildog0 View Post
https://youtu.be/C1SBVUoLZfo

Have you adjusted the TV cable? No need to take it to a shop for this.

Yes, I mistakenly called it "Throttle cable", above:
"Throttle cable has lots of puzzled mechanic's fingerprints on it...that's where their adventure begins, and then line pressure,......etc."

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  #97  
Old June 12th, 2019, 18:53
soyjer soyjer is offline
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Re: Please try this with your XJ and tell me results?

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Originally Posted by dsbhealer View Post
You can try an experiment to see if it is indeed the rear axle (from your video, it really looks like the rear axle to me). Block the wheels to prevent the jeep from rolling. remove the rear driveshaft from the rear axle pinion and then remove the driveshaft from the jeep by sliding it off the slip yoke. Put the transfer case in 4wd part time hi. With your foot on the brake, try shifting and see if there is less lurch and clunk with the front axle compared to what you were previously experiencing with the rear.
I just performed the experiment above...thanks for the suggestion...now I think that I can say for sure that the problem is not the rear driveshaft, differential, etc. The symptoms never fit for the problem to be behind/beyond the transmission input shaft, but hey..you never know.
The clunk/lurch is pretty much identical using only the front differential, including the "rebound" clunk that you can see in the my old posted video of the rear driveshaft movement.
Using the front differential only, when I shift directly from Reverse to Drive without pausing in Neutral, I get one minor clunk, and when I pause in Neutral before shifting to Drive I then get the same "violent" clunk/lurch (and also the same rebound clunk) that I get when using only the rear differential.

Regarding my question about whether the transmission input shaft turns when the transmission is in Neutral, I tried this: With the rear driveshaft still removed, I used 2H and Neutral to see if the rear transfer case output shaft would be turning at all, and sure enough it spins VERY slowly and steadily...and I can easily stop it with my hand. So I'm assuming that this means that MY torque converter turbine and transmission input shaft ARE turning with the transmission in Neutral, because otherwise what would be turning the transfer case rear output shaft? One would think that Neutral would completely 100% disconnect the transmission input from output, but either that is not 100% true or only MY transmission behaves this way. I'll need to find out if other people's XJ's behave this way or not, I guess, to find out it this is normal or not.
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  #98  
Old June 12th, 2019, 19:02
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devildog0 devildog0 is offline
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Re: Please try this with your XJ and tell me results?

Even with the trans and/or tcase in neutral there's still enough "drag" throughout the system though fluid and friction of other parts to cause things to turn when no resistance is applied to them.
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  #99  
Old June 12th, 2019, 19:43
soyjer soyjer is offline
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Re: Please try this with your XJ and tell me results?

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Originally Posted by devildog0 View Post
Even with the trans and/or tcase in neutral there's still enough "drag" throughout the system though fluid and friction of other parts to cause things to turn when no resistance is applied to them.
Thanks...yes...and of course, that would be true only if the torque converter turbine and transmission input shaft turn when the transmission is in Neutral...which I believe is true, and normal...but so far I haven't been able to verify that 100%.
Have you ever tried disconnecting the rear drive shaft, placing the transfer case in 2H and transmission in Neutral, and then seeing if the transfer case rear output shaft is very slowly and steadily turning, and then tried successfully to stop it by grabbing it, and then if you let go it starts turning again?
If you, or someone else, has been able to do this, then that would mean that it is likely normal for the torque converter turbine and transmission input shaft to turn when the transmission is in Neutral (in other words, there is no mechanism in an AW4 whose sole purpose is to stop the input shaft from turning in Neutral).
If it is normal for the torque converter turbine and transmission input shaft turn when the transmission is in Neutral, then that will eliminate one more possible source (input shaft momentum in Neutral in my AW4 that isn't supposed to be there) of my problem.
My motor mounts have been checked now by at least half a dozen professional mechanics, both general shop mechanics and transmission shop mechanics, but bad motor mounts sure do seem fit my symptoms...I'll make a video of my engine while shifting and post it here. Thanks.
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  #100  
Old June 12th, 2019, 20:09
lawsoncl lawsoncl is offline
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Re: Please try this with your XJ and tell me results?

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Originally Posted by soyjer View Post
Thanks...yes...and of course, that would be true only if the torque converter turbine and transmission input shaft turn when the transmission is in Neutral...which I believe is true, and normal...but so far I haven't been able to verify that 100%.



It's getting confusing with you running two threads on this. Yes, it is perfectly normal for the transmission output to freewheel a little bit in neutral when nothing is holding it.
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  #101  
Old June 12th, 2019, 20:14
trippled trippled is offline
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Re: Please try this with your XJ and tell me results?

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Originally Posted by devildog0 View Post
Even with the trans and/or tcase in neutral there's still enough "drag" throughout the system though fluid and friction of other parts to cause things to turn when no resistance is applied to them.
Agreed. The way a torque converter works, it is always applying some load to to the input shaft even in neutral. I've had cars at work I've left running in neutral that will actually forcefully creep forward. What you saw with the output shaft spinning I would say is completely normal.
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  #102  
Old June 12th, 2019, 20:39
soyjer soyjer is offline
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Re: Please try this with your XJ and tell me results?

OK...thanks for confirming. I'll check the mounts again and video the engine.
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  #103  
Old June 12th, 2019, 20:48
soyjer soyjer is offline
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Re: Please try this with your XJ and tell me results?

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Originally Posted by lawsoncl View Post
It's getting confusing with you running two threads on this. Yes, it is perfectly normal for the transmission output to freewheel a little bit in neutral when nothing is holding it.
Yeah...I'm trying to stick to this newer thread...I just needed to respond to dsbhealer over there cuz he had suggested the front diff test over there.
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  #104  
Old June 12th, 2019, 22:54
JXPEEJ JXPEEJ is offline
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Re: Please try this with your XJ and tell me results?

you are almost on to something here.
"My feeling that an un-braked input shaft in Neutral could cause the problem is based upon the momentum of the spinning input shaft in Neutral vs. no momentum of stationary input shaft in Reverse or Drive. Not saying it's necessarily the problem or that such a braking mechanism even exists...only saying that it fits the symptoms because pausing in Neutral is what causes the clunk/lurch to occur."
To make 1st gear forward clutch and low reverse clutches are applied.
To make reverse, direct clutch and low reverse are applied.
In neutral none of those are applied. forward and direct are driving clutches, low reverse is a holding clutch. IF the driving clutch comes on before the holding clutch, you get a harsh apply.
now when you pause in neutral you give the low reverse time to fully release . so you get to drive and the forward clutch comes on 1st, you get a bunch of trans parts spinning and then the low reverse clutch comes on and stops them from spinning CLUNK . Going the other way into reverse the direct and the low reverse timing is a better. So don't pause in neutral.
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  #105  
Old June 13th, 2019, 00:34
soyjer soyjer is offline
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Re: Please try this with your XJ and tell me results?

Quote:
Originally Posted by JXPEEJ View Post
you are almost on to something here.
"My feeling that an un-braked input shaft in Neutral could cause the problem is based upon the momentum of the spinning input shaft in Neutral vs. no momentum of stationary input shaft in Reverse or Drive. Not saying it's necessarily the problem or that such a braking mechanism even exists...only saying that it fits the symptoms because pausing in Neutral is what causes the clunk/lurch to occur."
To make 1st gear forward clutch and low reverse clutches are applied.
To make reverse, direct clutch and low reverse are applied.
In neutral none of those are applied. forward and direct are driving clutches, low reverse is a holding clutch. IF the driving clutch comes on before the holding clutch, you get a harsh apply.
now when you pause in neutral you give the low reverse time to fully release . so you get to drive and the forward clutch comes on 1st, you get a bunch of trans parts spinning and then the low reverse clutch comes on and stops them from spinning CLUNK . Going the other way into reverse the direct and the low reverse timing is a better. So don't pause in neutral.
I'm not understanding how the clunk/lurch would occur, due to the above, with the transmission output shaft held stationary by the vehicle. Wouldn't that prevent the transmission parts (other than the input shaft) from spinning?
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